Not sure if this is a bug or not, but just in case, I'm reporting it. Summary explains it pretty well; striders, unless on a lava block (source or flowing), will shake violently, similar to zombified piglins when in the overworld. Unable to provide an attachment due to not knowing how to take a video/gif, sorry!
Comments 6
Fun fact - Striders get cold when they're out of lava and shiver 😭😭😭
Confirmed, but I'm pretty sure that that's intentional. They're probably feeling cold if they're not near lava.